10 



BRITISH FERNS. 



the rachis is throughout naked, shining, and nearly black ; the 

 branches, or pinnae, are alternate, and on these are the pinnulae, 

 also alternate, and each on a distinct foot-stalk: botanists 

 describe these pinnulae as wedge-shaped, or fan-shaped, but 

 their form is not uniform, and often varies greatly in the same 

 frond. The fronds are fertile and barren. When fertile, the 

 exterior margin of each pinnula is divided into a number of 

 lobes, the terminal portion of which is bleached, scale-like, and 

 reflexed, and bears the thecae in somewhat circular masses on its 

 internal surface : this reflexed margin, and also the situation of 

 the veins, is shown in the detached pinnula to the left of the cut 

 in the preceding page : the veins divide frequently, and without 

 regularity, and run into the bleached reflexed portion of the 

 lobe, ceasing before its extreme margin, and each bearing a mass 

 of thecae at its extremity ; this will be seen on reference to the 

 lower figure of the cut in the preceding page, which repre- 

 sents only one lobe or division of the pinnula: the reflexed 

 portion turned back, and showing the masses of thecae, is 

 unshaded. When barren, which occurs but 

 seldom, the margins of the pinnulae, instead 

 of being bleached and reflexed, are sharply 

 serrated (as represented in the annexed figure), 

 and perfectly green to the extremity : with this 

 exception, the fertile and barren fronds are 

 similar. When the frond has passed maturity, and approaches 

 decay, the pinnulae of this fern fall off like the leaves of phaeno- 

 gamous plants, the rachis remaining bare and leafless, and 

 assuming the appearance of a bunch of strong bristles. 



Mr. Ball, of Dublin, informs me that this fern is so abundant 

 in the South Isles of Arran, that the inhabitants gather it, and 

 use a decoction of the fronds instead of tea : the same gentleman 

 pointed out to me a remarkable property it possesses, when 

 cultivated on Mr. Ward's plan, of checking communication with 

 the outer air by means of a glass cover ; the 

 lobes of the pinnulae become viviparous at the 

 extremities, the seeds actually vegetating while 

 still in situ, and the young plants taking root 

 like parasites in the substance of the old one: 

 from a specimen, in which this peculiarity was 

 clearly exhibited, I sketched the figure in the 

 margin. 



